Loud-speaker



- June 24, 1930.

L, H. DAVIS ET AL LOUD. SPEAKER Filed April 28.1930

Patented June 24, 1930 1 UNITED STATES:-

- PA'TENT OFFICE- LEWIS n. DAVIS, or nrrnn DARBY, AND RUSSELL 'r. xmesroan, or wYNcorE, rm-

BYLVANIA, ASSIGNORS T WATER KENT MANUFACTURING COMPANY, or

PHILADELPHIA, ?ENNSYLVANIA, .A. CORPORATION OF PENNSYLVANIA A noun-SPEAKER Application filed April as, 1930. Serial No. 447,786.

Our invention relates to amplifying telehones loud s eakers or radio 5 eakers phragm and coil assembly within the length.

particularly of the type having a coilmounted upon and moving with a soundreproducing diaphragm, specifically a hollow, truncated cone of suitable material.

In accordance with our invention, the

small open end of the cone is reinforced or strengthened, and preferably alsosecured to the cone-actuating member, specifically a coil form, by co-operating elements'or collars, preferably of metal, inv engagement with the inside and outside surfaces of the cone respectively and in opposing or clamping relation.

- The coil leads are preferably secured .to

the vibrating unit comprising the diaof a'flange element, specifically a clamping collar extension. More specifically, one of the elements or collars is an extension of, or integral with, 1 the coil form, and the other collar is attached to or" integral with a resilient cone centering disc, or equivalent, attached at its center, for example, to a stationary support, specifically a cylindrical pole piece,-orex tension thereof.

Preferably and. more specifically, the

small end. of the cone. terminates in a reentrant flange and receives the coilform,

a rim or collar portion-of the centering form.; Further in "member clamping the flange against the coil accordance with our invention,

prior to their en agement, co-operating.sur'-.

aces of either-t e cone, or of the reinforcing collars, or both, are coated with-glue,

cement, or the like. Our invention resides in. the features of construction, combination and arrangement hflCL to the accompanying drawings, in.

whicw'" Fig. 1, is a; side elevational' view, with elements.

cone 16.

parts in section, of an electro-dynamic speaker constructed in accordance w th our invention. 4

Fig. 2 is a fragmentary view on enlarged scale of parts shown in Fig.' 1. Fig. 3 is a front elevational View onv en larged scale, of the cone-centering element shown in Fig. 1. v

Figs; 4 to 8 inclusive, are detailedviews, onenlarged scale, of modified forms of-conesupporting and actuating ar'rangements- Referring to Fig. 1, to'th'e rear. wall 1', of

a housing or casing memlder 2, is secured electro magnetic structure comprising the field coil 3, disposed, within the cup-shaped housing4, preferably'of magnetic material, the bolt 5 threadably engaging the central pole piece 6 and extending exteriorly of the housing 2 where'it is engaged by the nut 7. -A spacingwasher 8, oir equivalent, of suitable thickness is disposed between the rear wall 1 of the housing'and the back plate 9 through back plate 9, frontplate -or pole piece. 11, and apertures in the supporting structure 12, tightening of. nuts 13 threadedon bolts 19 clamping'these elements together. To the outer edge, or periphery of .the

cone 16, of any suitable material, as parchment, Chinawood, or the like, is intimately attached as by adhesive, a flexible supportof the magnet assemblv. The bolts 10 pass H ing ring 17, of thin leather,-impregnated 'cloth, or equivalent, which is clamped-by bolts 18 between "the flange 19 of housing 2 and a protecting element or guard ring 20.

Preferably and as shown, the supporting element 12 for the front end f the magnetassembly terminates in anoutwardly. ex-

tending flange 12, through which the bolts 18 pass, sp acing washers 21- of suitable material beingsuitably interposed between the tures 23 inthe casing 2, and openings24 in the magnet supporting member 12, preventr .to the rear of the.

undue confiement of ai To conceal flanges 19, 12,; wa sh l ers 21, etcQthe guard element 20.;is provided with .the turned back edge 22. The aper 4 cylindrical coil form 25, of insulating material, for example, having a slot 'or groove- 26 in Whichis found the coil 27 traversed by currents Varying at voice frequency. To prevent their engagement withthe annular pole piece or front member 11 of the magnet structure, the leads 28,015 the voice coil 27 are disposed in one or more grOoves 2.) in the coil form 25. The turned back flangeor' re-entrant edge 30 of cone 16 snugly receives the forward end of coil form 25 and is clamped thereon by the rim 31 of the cone-centering and supporting element 32. The angle of the flange 33 of the centering member 32 is substantially the same or equals the angle of and engages the inner surface of cone 16. Preferably the reentrant edge v30 of the cone is coated on both sides with glue, cement or the like prior to engagement with the coil form 25 and clamping rim 31. r The elements are held in proper position by rim 31 during the drying period and it is not necessary as'in prior construction using glue alone to wait for the glue to harden before'r'elieving the cone and coil form from pressure, as by removal from a press.

In the finished diaphragm and coil form assembly, the inner end of the conical diaphragm overlying the metal flange 33' is rigidlyattached thereto so that at this region Within the length of the flange the diaphragm is incapable of flexure. This same condition obtains with the other modifications hereinafter described.

. The leads 28 fromthe voice coil which may be extensions of the flexible conductor forming'the coil or flexible wires connected to theterminals ofthe coil-are secured by any suitable means, as by a dab of adhesive, or cement, or as indicated by'a strip of adhesive tape 14,.to the vibrating unit consisting of the diaphragm and coil assembly to 1 that part of the diaphragm overlying and 1 Heretofore it has been the practice to constifl'ened by the flange 33.

The free ends'of the leads are connected to suitable terminals 15, 15 which may as illustrated be mounted upon a block of-in-' sulatio'n secured to the suppo-rtingstructure 12. The inner ends of the leads 28 are attached or anchored at a point within the extent of the rigid conical flange 33 and are there fixed with respect to the coil 27, and partake of movements or vibrations equal to the movements or vibrationsof the coil.

' struct the centering element or-spid'er 32 of fibre and to glue it directly to the cone. Aided in some cases by atmospheric conditions, the strain incident to the large amplitude of movement characteristic of this type of speaker has broken orweakened the connecv tion between the cone. and the centeringelement effectedsolely by glue.

Referring. to Fig. 3, the centering member tion. The top or spider portion of the element is formed by a piercing or stamping operation and its resilience may be increased,

if desired, as by suitable hammering operations. The inner spring-arms 34, and the outerspring-arms 34 are so proportioned in length as to more equally distribute the load between them and to permit greater ampli? tude of movement ofi'cone 16. A machine screw 35 or equivalent passes through the central aperture 36 of the centering member 32 and threadably engages an extension 37 of the pole piece '6, clamping the spider tightly against the projection, and support-,

ing the cone and coil form so that the latter is freely movable rectilinearly in the air gap between the pole pieces 6 andll. The centering of the coil permits its movement with out change in position transversely of the air gap, and precludes the possibility of its coming 1nto contact with either or both pole pieces. Since the small end of the cone is rigidly connected to the coil form and the base or large end ,of the coil is supported by the flexible ring 17, all parts ofthe cone or diaphragm vibrate at amplitudes equal to the amplitudes of movement of the coil itself. The metalspider is not subject to the warping and stretching of fibre board spiders heretofore commonly used.

In the modification of my invention shown in Fig. 4, the coil form-25 is ofmetahas German silver, brass, or the like although it may be of insulating material, as fibre, bakelite, etc; .The coil 27 may be wound on the form in a region of smaller diameter, between the rolled-back edge 38 and shoulder 39. The coil form of Fig. 2 may be also constructed in like manner and of metal. This modification differs. from that of Fig. 2 in that the rim 31 of the centering member 32 engages the coil form rather than-the reentrant edge of the cone 16. Preferably glue or equivalent is used to strengthen engagevment between the coil form 25 and the rim 31,1n which event it is desirable to use a paper gasket therebetween to obtain a fast andv durable union of these elements. The

able fixed terminals as previously described.

vAs in the prior modification glue, cement /or equivalent is or maybe utilized to supplement the clamping rings to 'eflect ri'gidityfof;

the assembl structures. To stiffen the thin metal windlng form 25*, both ends may be rolled, the edge remote from the cone being turned outwardly to hold the windings in place, as above described.

In the modification of my invention shown in Fig. 5, the winding form 25 'is integral with the centering member 32, and may, as in the preceding modification, be of metal, with or without a portion of smaller diameter for receivin the turns of the voicecoil 27. The rein orcing ring 40, preferably of metal, holds the re entrant portion 30 of the cone 16 tightly against the periphery of the windin bein reinforced by no or cement, i sired, as previously escribed. The flange 41 adhesively attached to the 'cone 16 reinforces and stifiens it. The coil leads 28 are anchored to the diaphragm within the conical length of flange 41 and extend therefrom to fixed terminals 15,- 15.

The arrangementshown in Fig. 6 is similar to that of Fig. 2 in that the spider 32 and the flange engaging the inner face of the cone 16 are integral, the spider of the centering member 32, however, in this modi-. fication being larger. The external diameter of the form in the region engaged by the winding 27 is the same as that of coil form 25, the greater diameter of the the cone portion engaging the re-entrant edge 30 of portion 42. Preferably, and as shown, the turned back portion .is formed with a flan e 43 co-operatm with the flange 33 of tfie centering mem er 32 further to strengthen and reinforce the connectionbetween the (zone 16, the' centering member 32,'and the coilform 25. The leads from .the coil are secured to and insulated from the flange .if desired, and particularly when the resili- 43 -in any suitable manner and from that point of-mechanical connection extend from the vibrating system to binding points mounted upon a stationary support, as disclosed in Fig. 1. If necessary or desirable, the-metal coil form of Figs. 4, 5 or 6' may be slotted, as indicated in Fig. 6. The apertures or slots '44 ordinarily will extend longitudinally of-the coil form.

. When the cone is of a more or lessbrittle ent spider 32 is of larger area, be of suitabl larger diameter than the portion ,on who the 'coil 27 is wound and" preferably is form 25 the 'oint deng eflected by turning back the metal to form the reversely extending formed with a flanged extension 43 which e'ngages the outside surface of the cone. Further to strengthen the small end of the conical diaphragm 16, the centering member 32 maybe provided withfiange 33 extending outwardlyv from the rimto suitable extent. The diameters of ri'm 31, and collar 46, and'the thickness of the cone 16 are preferably such that appreciable force' must be'applied to the centering element 32 to effect the relation between the parts shown in Fig. 7. The leads 28 as indicated the small end of the cone, extending therefrom to binding posts or equivalent. As

in the prior modifications the union between ivalent may be these members or their .egu

strengthened by suitable a hesive.

In the modification of my invention' it 1s provided with a cylindrical. portion 31 and an angularly disposed flange ortion 33. The coil form 25- is, however in this modification directly engaged, and internally, by the rim 31 and forced into contactwith the outwardly extending cylindrical extension 45 of the cone 16. The collar 47 clamps the cone end 45 against coil form 25 and the portion of. the cone adjacent this region against flange 33 of the centering member 32. The coil leads 28 are secured to the 'flanged portion of the outer collar .are attached tothe flange 45 which overlies 47 in a manner similar to that described for the other modifications.

In Figs. 2,4, and 5 to 8 inclusive, engage ment between the coil form, cone, etc. may

be in any sequence or simultaneous, as may" be desired orexpedient in. view of the assembling tools, or machines, etc.

What we claim is:

1. A tele honic sound reproducer comprising a iaphragm substantially of the shape of a truncated cone and'terminating in an inwardly directed flanged portion, annular reinforcing collars engaging opposite sides of. and clamping said flanged portion between them, and a reticulated centering disc integral with one of saidcollars andextending across the area bounded thereby.

2. A ..teleph0nic sound reproducer com prising a diaphragm substantially,- of the shape of a truncated cone and terminating in a re-entraht flange, a coil form, having a collar portion operatively related to one side of. said flange, an element. having a collar portion operatively related to the other side of said flange and cooperating with said first named collar portion to secure the diaphragm to said coil. form, and a" reticulated centering, disc integral with and e'xtending'across the area bounded by 7 one of said-collar portions.

3. A telephonic sound reproducer comprising a conical diaphragm, a,cylindrical' coil form, means to secure the coil form to the small end of said diaphragm comprising a cap having a cylindrical portion and a resilient end portion comprising a slotted disc, and means to secure the central portion of said disc to a stationary member;

4.. A telephonic sound reproducer comprising a conical diap'hragm' having a reentrant flange at its small end, a coil iorm over-lapping said flange, and a cap member having a rim portion cooperating'with said coil. form to efiect operative connection therewith of said flange, and an end portion slotted to provide spring arms.

5. A telephonic sound reproducer 'comprising a truncated cone diaphragmhavin a re-entrant flange'at the small end thereo a coil form received by said flange, and a metal cap having a col a ing with said coil form to secure said flange thereto, and an end portion slotted to'provide spring arms.

6. A telephonic sound reproducer com-.

prising a truncated cone'diaphragm having a re-entrant flange at the small end thereof,

a coil form received by said flange, and a metal cap having a collar portion effecting connection of said flange and said coil form, a flange having substantial area of contact with said cone adjacent the re-entrant flange thereof, and an 'end portion slotted to provide spring arms.

7. A telephonic sound reproducer comprising a diaphragm substantially of the :shape of a trunacted cone terminating in a flanged portion, a coil form over-lapping said flange, a cap-member having a rim por- 7 tion cooperating with said coil 'form to ef- "fect operative connection therewith of said v flangeand a resilient end portion, and a means to secure said cap at substantiallythe center of said end portion to a stationary member. v

8. A telephonic sound reproducer comprising a conical diaphragm, a cylindrical H coil form, means'to securethe coil form to the'small end of said diaphragm comprising a cap having a--cylindrical portionand a resilient end portion comprising a disc,

and means to secure the disc substantially fit its central portion to a stationary memer I 9. In telephonic apparatus,: a vibrating unit comprising a comcal diaphragm anda coil, a form for said-coil, means for securing said form to said diaphragm comprising a conical flange element engaging sa1d'diaphragm, and a flexible connection from said coil to the external circuit and attached to said unit within the conical length of said flange. v

, LEWIS H. DAVIS. RUSSELL'T. KINGSFORD.

1' portion cooperat 

